Hitherto, there has been known a differential gear in which a pair of pinion gears and a pair of side gears which are each a straight bevel gear are meshed with each other (see Patent Document 1, for example). The pinion gears forming the differential gear have ten teeth, and the side gears have 14 teeth. The differential gear is configured such that extensions of the tooth tips of the pinion gears and the side gears pass through the intersection between the axes of the pinion gears and the side gears. This allows the line of simultaneous meshing between the pinion gears and the side gears at the start and the end of meshing therebetween to extend over the entire region from the large-diameter end portion to the small-diameter end portion of the straight bevel gears, which suppresses concentration of a meshing load only in the vicinity of the large-diameter end portion.